1. Field of the Invention
The present invention relates to a display method for laser irradiation state and a display system of laser irradiation state and in particular, relates to technology suitable to carry out teaching operation and the like, in advance of process of welding and the like, to a work.
2. Description of the Related Art
Recently, laser welding has been used also in welding utilizing a robot. As such welding technology, there has conventionally been such technology as carrying out welding rapidly with high degree of freedom in an irradiation direction, by means of stopping a laser irradiation part attached at the tip of a robot handle, apart from a welding point while varying the laser irradiation direction by means of rotating a reflecting mirror inside the laser irradiation part, to carry out welding by irradiation of laser light at a work.
To obtain high welding quality in such laser welding, alignment of a laser irradiation part at a specified position is required so that laser focuses at a welding point of the work surface, as well as laser is correctly irradiated at the welding point. As a result of such alignment, action of the robot is set in advance by CAD simulation so that the laser irradiation part is aligned at the specified position usually in welding.
However, disjunction may generate between action of a robot predicted by a simulation and a real action of a robot, due to error of inertial force and weight, and the like, of a robot. Generation of this disjunction may result in non-alignment of the laser irradiation part at an adequate position, irradiation of laser at a point other than a welding point, or non-focusing of laser at a welding point, which leads to lowering of welding quality. To avoid such troubles, confirmation of practical laser irradiation state is required in teaching operation of movement of a robot in advance.
JP-A-2004-130334 has disclosed technology enabling to confirm practical laser irradiation state in teaching a position of laser irradiation state. In this technology, a contact type displacement gauge is installed, which is protruded from the tip of a laser irradiation part by length equivalent to focal distance of laser in a laser irradiation direction. Then, by contact of the contact type displacement gauge with a welding point of a work, information on a position of the laser irradiation part (that is, a position of the laser irradiation part in the state of laser focusing at a welding point) is obtained, and based on the information, a position of the laser irradiation part is adjusted to enable focusing of laser at a welding point.
However, although the conventional technology is applicable to the case when a laser irradiation direction is constant and distance between the position of laser irradiation and a work is close, in the case when a laser irradiation direction is required to be varied, angle thereof cannot correctly be monitored, and also in the case when distance between the position of laser irradiation and a work is apart, generation of bending of the contact type displacement gauge makes correct measurement impossible, and workability becomes poor because contact of the displacement gauge with a work is required always.